The invention is based on a device and a method for determining parameters of a welding system according to the general class of the independent claims.
A method for evaluating resistance-welded joints is made known in DE-A 43 25 878. In order to evaluate welding procedures on-line, the ultrasonic permeability of the welded joint is determined by acting upon it with distortional waves. To this end, the mean ultrasonic energy is determined—during each current half-wave of the welding current—from the output signal of the ultrasonic receiver within a time window that is delayed by a defined lag time as compared with the constant ultrasonic transmitted signal. Said mean ultrasonic energy is used as a measure of the quality of the welded joints. To regulate the welding process, the variation of the ultrasonic permeability can be compared with a prespecified sample trace in order to change the welding parameters, e.g., current intensity, accordingly if a deviation occurs, so that the subsequent ultrasonic permeability values can conform with the sample trace once more.
The object of the invention is to determine further parameters relevant for the welding procedure that provide an indication of the condition of the welding system. It is desirable, in particular, to determine the wear of an electrode of the welding system exactly so that it can be displayed or so that maintenance intervals for the electrodes can be stated automatically. It will also be made possible for the closed-loop control system to take the aging process of the welding electrode into account.
This object is attained by means of the features of the independent claims.